Why does my view not change after published variable is updated? – Ios swift

Once a user logs in to my app, I want to change the view from SignInView to AppShellView. The authData variable updates perfectly fine in UserViewModel once it receives data from the API (checked in UserViewModel via print statement) but this update is not being reflected in ContentView as it always shows the SignInView.

Why is authData not being updated in ContentView?

UserViewModel:

import SwiftUI

struct LoginRequestBody: Codable {
    let email: String
    let password: String
}

struct AuthData: Codable {
    let token: String
    let loggedInUser: User
}

class UserViewModel: ObservableObject {
    // MARK: - PROPERTIES

    @Published var authData: AuthData?
    
    // MARK: - FUNCTIONS
    
    func signIn(email: String, password: String) {
        guard let url = URL(string: "http://localhost:4000/api/users/login") else {
            return
        }
        
        let body = LoginRequestBody(email: email, password: password)
        
        var request = URLRequest(url: url)
        request.httpMethod = "POST"
        request.addValue("application/json", forHTTPHeaderField: "Content-Type")
        request.httpBody = try? JSONEncoder().encode(body)
        
        URLSession.shared.dataTask(with: request) { [self] data, response, error in
            guard let data = data, error == nil else {
                return
            }

            guard let loginResponse = try? JSONDecoder().decode(AuthData.self, from: data) else {
                return
            }
            
            self.authData = loginResponse
            
            if let encoded = try? JSONEncoder().encode(self.authData) {
                let defaults = UserDefaults.standard
                defaults.set(encoded, forKey: "authData")
            }
        }.resume()
    }
}

ContentView:

import SwiftUI

struct ContentView: View {
    @ObservedObject var userViewModel = UserViewModel()
    
    var body: some View {
        if userViewModel.authData != nil {
            AppShellView()
        } else {
            SignInView()
        }
    }
}

Edit:
The problem seems to be the following: While the code successfully creates the authData object in UserViewModel, it cannot share its updated state outside of UserViewModel (despite being declared as @Published) no matter in which other struct or view I try to use it.